1. Field of the Invention
The present invention relates to the field of display technology, and in particular to a BOA (Black Matrix on Array) liquid crystal display panel and a manufacturing method thereof.
2. The Related Arts
With the development of the display technology, liquid crystal displays (LCDs) have been widely used in various consumer electronic products, such as mobile phones, televisions, personal digital assistants (PDAs), digital cameras, notebook computers, and desktop computers, due to a variety of advantages, such as high image quality, saving power, thin body device, and wide applications, and are now the main stream of display devices.
Most of the liquid crystal displays that are currently available in the market are backlighting liquid crystal displays, which comprise a backlight module and a liquid crystal display panel mounted to the backlight module.
A liquid crystal display panel used in a thin-film transistor liquid crystal display (TFT-LCD) is generally made up of a color filter (CF) substrate, a thin-film transistor (TFT) array substrate, and a liquid crystal layer arranged between the two substrates and the principle of operation is that a driving voltage is applied to the two substrates to control rotation of the liquid crystal molecules of the liquid crystal layer in order to refract out light emitting from the backlight module to generate an image.
The TFT, which is an important constituent part of an array substrate, is an insulated-gate field effect transistor made of a semiconductor film and comprising an active layer that is extremely sensitive to light so that even a small variation of light intensity would greatly affect the characteristics of a TFT device. When conducted on, a TFT would generate a photo leakage current (Photo loff) in the active layer between a source terminal and a drain terminal due to irradiation of faint light. When photo loff increases, the characteristics of the TFT device gets deteriorated, leading to the problems of cross-talking, flickering, and residual image so as to greatly affect the quality of displayed images.
As shown in FIG. 1, a conventional liquid crystal display panel comprises an array substrate 100 and a CF substrate 200 that are opposite to each other and a liquid crystal layer 300 interposed therebetween. Formed, sequentially from bottom to top, on a surface of the array substrate 100 are a lower substrate 110, a gate terminal 120, a gate insulation layer 130, an active layer 140, source/drain terminals 150, a passivation protection layer 160, and a pixel electrode 170, wherein the gate terminal 120, the gate insulation layer 130, the active layer 140, and the source/drain terminals 150 collectively constitute a TFT; and arranged on a surface of the CF substrate 200 are an upper substrate 210, a black matrix (BM) 220, a color resist layer 230, and a common electrode 240. The black matrix 220 that is light impermeable is arranged on one surface of the CF substrate 200, this being the so-called “BM On CF” and the black matrix 220 is located above and corresponds to the TFT, a gate line, and a data line to shield light leaking at the sites of the TFT, the gate line, and the data line in order to maintain displaying quality.
However, such a “BM On CF” liquid crystal display panel does not shield light emitting from a backlight module that is located under the array substrate 100 toward the active layer 140 and thus, inevitably, a photo leakage current would be induced and the performance of the TFT device and the quality of a displayed image would be affected. Further, in an operation of laminating the array substrate 100 and the CF substrate 200, precise alignment of the black matrix 220 with respect to the TFT, the gate line, and the data line is hard to achieve. Further, the number of masks used in manufacturing the liquid crystal display panel is great and the manufacturing time is long so that the manufacturing cost is high.